This is only tangentially related to what you just said, but I find adaptations fascinating because of how permeable the concept of "staying true to the source material" is.

One of the best examples I can think of is the animated movie Nimona, based on a graphic novel (that started as a webcomic) by N.D. Stevenson. The movie changes a heckton from the graphic novel, but in a way that arguably leads to a more authentic adaptation of the "soul" of the graphic novel. An example from the inverse is Shyamalan's adaptation of Avatar: The Last Airbender: there were parts that were copied over, shot for shot, from the animated show, and even this segments that closely followed the source material just didn't work — things that worked in animation don't work in live action and vice versa.

I don't think there's any one interpretation of what the "soul" of a piece of media is, but watching Velma was perplexing because I wondered whether Kaling had actually wanted to make an adapted spin-off, or whether this was a completely separate show that later had a Scooby Doo veneer put on top. I wish I could've better understood what her vision was, because I can't see what, if anything, resonated with Kaling from the original media.